European Union antitrust regulators Thursday hit Facebook with a $122 million fine — one of the largest penalties it has ever received — for misleading them about its acquisition of messaging service WhatsApp in 2014.

Officials said the penalty also sends a warning to other companies.

“Today’s decision sends a clear signal to companies that they must comply with all aspects of EU merger rules, including the obligation to provide correct information,” said Margrethe Vestager, the EU’s commissioner for competition, in a statement.

The Menlo Park tech firm told the European Commission, the executive arm of the EU, in 2014 that it couldn’t automatically match Facebook users’ accounts to WhatsApp users’ accounts.

But the commission found out that wasn’t true. It said that Facebook’s staff knew it was possible to match accounts, but failed to inform the commission.

Last year, when the messaging app updated its terms of service and privacy policy, WhatsApp said it could link users’ phone numbers with Facebook users’ identities.

Facebook said in a statement that the errors it made were not intentional and that the commission confirmed it didn’t impact the outcome of the merger review.

“We’ve acted in good faith since our very first interactions with the Commission and we’ve sought to provide accurate information at every turn,” Facebook said in the statement.

Facebook purchased WhatsApp, which now has more than 1 billion users in over 180 countries, for $22 billion in 2014.

The commission said in a press release that it fined Facebook for providing incorrect and misleading information in the merger notification form and in a reply to the commission’s request for more information.

“The Commission considers that these infringements are serious because they prevented it from having all relevant information for the assessment of the transaction,” according to the press release.

This isn’t the first time that Facebook has landed in hot water with European antitrust regulators. The company has also faced privacy concerns over the data it collects from its users.

This week, a French regulator, the Commission Nationale de l’Informatique et des Libertés, slapped Facebook with a $164,000 fine for running afoul of the country’s data protection rules.

Queenie Wong covers social media businesses, including Facebook, Twitter and LinkedIn, for The Mercury News. She grew up in Southern California and is a graduate of Washington and Lee University where she earned bachelor's degrees in journalism and studio art.

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